Abstract
Biochemical and morphological investigations were made on erythrocytes from two patients homozygous for genetic hypobetalipoproteinemia. Increased ratios of cholesterol/total phospholipids and sphingomyelin/phosphatidylcholine, and decreased membrane lipid fluidity were detected in the patients' cells as compared with those from a normal adult. Typical acanthocytes were observed which comprised 10-15% of each cell population of the patients. Such acanthocytosis was not corrected by incubation of the cells with either normal plasma, purified LDL, or phosphatidylcholine liposomes, but was corrected by treatment with phospholipase C which caused stomatocytosis of the cells. Incubation of the patients' cells with echinocytogenic agents such as flufenamic acid and lysophosphatidylcholine yielded more intensive echinocytosis than occurred with normal cells. Incubation of the former with a stomatocytogenic reagent, chlorpromazine, yielded weaker stages of stomatocytes than in the case of the latter.
These results suggest that the acanthocyte shape may not simply result from the abnormal lipid contents of the cell membrane, and that not only the observed acanthocytes are abnormal but also the other normal-looking cells of the patients may have some abnormalities in their membrane structure.
